ELECTRICITY FROM SWEATY FINGERTIPS?

This device takes power from your sweat while you sleep.

A team of US researchers has made a tool that can generate electricity from sweat. Worn as a cap on a fingertip, it could be used to power small medical devices while subjects sleep.

Engineers around the world have previously explored the potential of human sweat to generate energy. But other devices are “hindered by the inherent inaccessibility of natural sweat”, according to a paper in Joule. While this new device doesn’t generate much electricity, it also doesn’t need much sweat to work: it can be powered from passive activities.

The 1cm2 device uses a compound in sweat called lactate. When oxidised, the lactate releases a small amount of energy. It can collect 300 millijoules from a centimetre of skin over a 10-hour sleep period, or 30 millijoules from the press of a fingertip. While it won’t be charging your smartphone anytime soon, it’s enough energy to power small wearable medical devices – in their paper, the researchers used it to run vitamin C and sodium-sensing tools.